FR2689188A1 - Device opposing adjustments for an adjusting screw. - Google Patents

Abstract

A device opposing adjustments for an adjusting screw (2a, 2b), retained so as to be able to rotate in a body (1), in particular of a carburetor, consists of a cap (4) fixedly retained in rotaion on the head (3) of the adjustment screw (2a, 2b), and by an annex part (5) provided on the cover (4) and to which is associated. in the direction of rotation of the adjusting screw (2a, 2b), a stopper integral with the body (1). So that in the event of manipulation of the adjustment screw the device is destroyed without fail, the cap (4) is surrounded, with a slight radial play (r), by a sleeve (9a, 9b) arranged coaxially to the cap. According to the invention, the cap is received entirely in the sleeve and the latter is connected, at one of its ends, to the cap (4) or to the part (17) of the body having the stop.

Description

i

  Device opposing adjustments for a retaining screw

  The present invention relates to a device opposing the adjustments for an adjustment screw retained so as to be able to rotate in a body, in particular for an adjustment screw of a carburetor, for example a diaphragm carburetor or the like. '' a machine tool such as a chain motor saw, the device being

  consisting of a cap fixed in a fixed manner in rotation

  tion on the head of the adjusting screw, and by an annexed part provided on the cap and which is associated in

  the direction of rotation of the adjusting screw a stop so-

of the body.

  Carburetor adjustment screws are subject to

  linked by a device oposing Adjusting them to avoid any unauthorized operation of the step screw

  vacuum or main adjustment screw In machi-

  tools equipped with a two-stroke engine

  Glage must however remain maneuverable in order to

  see by setting an optimal motor performance according to external operating conditions such as

  for example the altitude of the place of use When

  adjustment adjustment it is also necessary to take care of the quality of the exhaust gases in order to avoid pollution

useless from the surrounding environment.

  Thanks to American patent US-A 3618906, a device is known to oppose adjustments for a

  adjusting screw of a carburetor, which device is

  set up by a cap which, axially secured in shape connection and fixedly fixed in rotation on the head of the adjusting screw, has an annexed radial part

  which cooperates in the direction of rotation of the screw

  gliding with a stop secured to the body After a preset

  carburetor age the cap is pushed into place captively on the adjusting screw so that it remains

  11 f_ 1 iqu'une possibility of adjustment in the "lii-

  tes of the displacement angle determined by the part an-

  fixed and by the stop integral with the body This possibility of

  adjustment is such that the quality of the exhaust gases

  stop at a low level of environmental pollution

nant remains insured.

  The limitation of the possibility of maneuvering a

  adjustment screw, especially in the case of carburetors

  two-stroke engines of machine tools, is in practice

  that often deleted in order to be able to adjust, without keeping

  poor quality exhaust gas account, the

  engine power desired by a user When checking the devices opposing the adjustments of the screw, most often removed by lifting up an an

  screwdriver, are replaced so that the handles

  carried out are not directly recognized

visually.

  The object of the present invention is to enable a device opposing adjustments of the defined type.

  higher and offering a limited adjustment path allowed from

  be perfected in such a way that it is not possible

  ble, without destroying said device, to remove, by means of

  ons of lever, the cap limiting the authorized adjustment path.

  This goal has been achieved with regard to a provision

  opposing the adjustments of an adjustment screw

  held so that it can rotate in a body, in particular

  bind for a carburetor adjustment screw as per

  example a membrane carburetor or the like of a machine

  ne-tool such as a chain motor saw, said device

  sitive being constituted by a cap retained in fixed rotation on the head of the adjusting screw and by an annexed part provided on the cap and to which is da S the rotation of the adjusting screw a stop integral with the body , according to the invention by the fact that the cap is surrounded, with a slight radial clearance, by a sleeve disposed substantially coaxially with the cap, that

  the cap is received substantially over its entire axial length

  ale in the socket and that the socket is connected to the cap

  fe or to the part of the body presenting the stop.

  Since the cap is completely surrounded

  of the socket and received in the socket, a tool

  putting to remove the cap by a lever action can not be directly applied to the end, body side, of

  the cap without causing visible permanent damage to it

  last or at the socket A manipulation carried out or

  even only attempted of the device opposing d A C rajl Cs-

  Unauthorized actions can therefore be ascertained at any time so that countermeasures can be taken. According to another characteristic of the invention

  the end of the cap which is far from the body and the ex-

  end of the socket which is away from the body ends

  more or less in a common plan.

  In an advantageous embodiment of the invention, the end of the socket which is distant from the

  body is connected, via radiators

  those intended to break, at the end of the distant cap

  body and the end, on the body side, of the sleeve extends as close as possible to the part of the body having the stop. In this embodiment, the spacers intended to break are advantageously located in the

aforementioned common plan.

  Tools for the manipulation or removal, by a lever action, of the cap cannot therefore be used Without cxcrc = r an Eforce on the sleeve * given

  that under the effect of such a force the spacers intended

  born to rupture and constituted in particular by a ma-

  fragile plastic material breaks, handling is effected

  killed or tempted remains visually recon-

  birthable so that it can be recognized at any time

  tee Since the socket is at a low dis-

  radial tance of the cap, forces acting radially on the device opposing the adjustments also lead to a deformation of the bushing and, consequently, to the destruction of the spacers intended to break The fact for the device opposing the adjustments not allowed to be gripped by forceps or the like, remains

  according to the invention also permanently visible.

  Preferably, there is provided in the bottom of the cap, on the side remote from the body, an engagement opening for an operating tool so that the operating forces act exclusively on the cover and are

  transmitted, via the annex, direct

  tally to the stop integral, in rotation, with the body A sim-

  full assembly in friction connection of the cap and the head is sufficient since the connection between the head and

  the cap remains free of operating forces.

  The part of the body, fixed in rotation and present

  both the stop is in particular a screen crossed by the adjusting screw or, preferably, by two adjusting screws and which, before the fitting of the cap, is slid over the protruding end of the adjusting screw After setting

  in place of the cap the screen is retained axially-

  captive between the cap and the carburetor body.

  Consequently, existing carburetors of all kinds can easily be retrofitted with the device.

  opposing the adjustments provided according to the invention.

  Another characteristic of the invention consists in that the carburetor body and the body-side end of the bush overlap axially. In an advantageous embodiment of the invention the abovementioned stop is located between the sleeve and

The hairdo.

  Another characteristic of the invention consists

  in that the annex part extends, roughly parallel-

  to the axis of the adjusting screw, axially in the direction

  of the carburetor body, the sleeve preferably being

  aligned in one piece with the part of the body presenting the stop. In an advantageous embodiment of the invention the abovementioned stop is formed by one end of a slot which, formed in the part of the screen body and extending in the direction of rotation, is longer, in the direction of rotation, that the annex part

  axial, which extends over a peripheral angle of pre-

ference of around 900.

  Advantageously, the cap is retained in dynamic connection on the head of the adjustment screw and there is provided, in particular on the side of the bottom of the cap remote from the body, an engagement opening for an operating tool.

  The invention is explained in more detail below.

  below with the aid of exemplary embodiments illustrated in the appended drawings in which:

  Figure 1 shows, in section, two arrangements

  tifs opposing the adjustments, mounted on adjustment screws; Figure 2 shows a section along line II-II of Figure 1;

  FIG. 3 represents, in top view, a device

  positive opposing the adjustments according to Figure 1; Figure 4 shows, in section, a device

  opposing adjustments fitted with a fixed bush in

  tation; 5 shows a section along the line V-V of Figure 4;

  FIG. 6 represents, in top view, the device

  positive opposing the adjustments in Figure 4;

  FIG. 7 represents, in section, another example

  full realization of a device opposing the readjust-

ment; and

  FIG. 8 represents, in top view, the device

  positive opposing the adjustments according to figure 7.

  The devices opposing the adjustments

  shown in Figure 1 secure adjustment screws 2 a, 2 b, retained so that they can rotate in a body 1 The adjustment screws can be the idle adjustment screw, the main adjustment screw or screws similar adjustment equipping a carburetor such as for example a diaphragm carburetor or the like

  are used in internal combustion engines, in particular

  especially two-stroke engines, which are used in

  as drive motors in a machine tool

  me for example a chain motor saw, a chainsaw

  at labial, a dblroussailleuse or r Lachines-ou Lils g-yïi-

  manually analogous dices The adjustment screws 2 a and 2 b are screwed into the body 1 of the carburetor Their terminal parts 3 a and 3 b protruding from the body 1 have a

  reduced diameter and have an annular shoulder 22.

  The free end of the terminal part 3 a; 3 b forms the

  head 3 of the adjusting screw in the front face 23 of the

  which is provided an engagement slot 24 for the

  pledge of an operating tool such as a screwdriver or the like The head 3 is offset relative to the part

  remaining terminal by a peripheral groove 25.

  When the adjustment screws 2 a and 2 b are correct

  tightly slipped on their end portions 3 a and 3 b a common screen 17 so that the end portions 3 a and 3 b pass through through holes 26 of the screen 17 On the side of the body 1 the screen 17 takes press at least

  an annular shoulder 22; due to the two adjustment screws

  ge 2 a and 2 b clamped in the body 1 the screen 17 is an ele

  integral with the body and fixed in rotation in the direction

  rotation of the adjusting screws 2 a and 2 b In case of use

  reading a single screen by adjusting screw, the screen should be fixed in rotation to the body 1. The through holes 26 are made so as to be widened at their ends 26 a; 26 b located on the side

  of the head 3 In the periphery of the through hole 26 is met

  a slit 28 which extends over part of the perimeter

  and is axially open towards the extremi-

  widened tee 26 a; 26 b The slot 28 can therefore also be designated as being a slot 18 formed axially in the shoulder 27 and which extends over a peripheral angle 19. e

  In the slot 18 an axially protruding part

  attachment 5 of a cover 4 fixedly fixed in

  tation on the head 3 of 'The adjustment screw 5 a 2 b For purposes of securing fixed in rotation the head 3 carries an external knurling which when the cap is put in place by pressing engages in the plastic there

  it may be advantageous to provide in the cover 4 a knurling-

complementary age.

  At its end, facing the body 1, the cap has an inner lip 29 which engages in

  the peripheral groove 25 and retains the axial cap 4 -

  ment in captive form in a captive manner on the adjusting screw 2 a, 2 b The lip 29 can be produced as

that arresting body.

  As shown in Figure 2: 3 has slot 1 R pro-

  feels a peripheral angle 19 which is larger than the an-

  peripheral gle 20 on which the annex part 5 extends.

  In the exemplary embodiment shown there is provided a

  peripheral angle 19 of 1800, while the peripheral angle

  that 20 is 900 The ends of the slot 18 arranged in the peripheral direction form stops 6 and 7

  integral with the body and against which the part an-

  nex 5 in the form of a partial sheath Due to the dimensions chosen for the peripheral angles 19 and 20, the adjustment screw 2 a is obtained; 2 b, the cap 4 having been put in place, an adjustment angle 21 of 900, that is to say a

  quarter turn rotation By choosing a length ap-

  suitable for slot 18 and the periphery of the an-

  end 5, it is possible to obtain an adjustment angle 21 of approximately 3500, that is to say an admitted displacement of almost a whole revolution. In the bottom 15 of the cap 4 is formed, on the side remote from the body 1, an engagement opening 16, preferably an engagement slot for an operating tool such as for example a screwdriver or the like By means of dc 1 the ma-noauvre tool is arranged in the engagement opening 16 the adjusting screw 2a; 2 b secured by the cover 4 can be moved in the angular interval

  area of the adjustment angle 21, so that the

  these displacement exerted act exclusively on the cover 4 and its annex part 5 extending parallel to the axis 8 of the adjustment screws 2 a and 2 b The solid dynamic connection between the screw head 3 and the cover 4 is free of

maneuvering forces.

  The adjustment cap 4 is surrounded by a socket 9 a; 9 b which is coaxial with the cap 4 and therefore with the axis 8 of the adjusting screw Between the outer periphery of the cap 4 and the inner periphery of the sleeve 9 a, 9 b

  a short radial distance r is provided.

  The end 10, remote from the body 1, from the bushing

  9 a; 9 b is connected, by means of spacers 12 intended to be broken (FIGS. 1 and 3), to the end 13 of the cover 4 The end 10 of the socket 9 a; 9 b and the end 13 of the cap 4 substantially end

  in a common plane 14 in which are preferably

  this also the spacers 12 intended to be broken.

  The plastic cover 4 and the socket 9a; 9 b eg-

  They can also be made of plastic.

  between them by means of spacers intended

  to be broken and which are arranged for example mid-lon-

  axial direction This may be advantageous from the point of view

injection molding technique.

  In the device opposing the adjustments

  by rotation, represented on the left in FIG. 1, the end

  mity 11 of the socket 9 a, located on the side of the body 1, is

  found in the immediate vicinity of part 17 of the body

  both the stop In the embodiment shown the distance a from the end it to the part 17 of the body is dimensioned in such a way that the residual slit is

  too narrow to be engaged, radially up to

  that at the end 28 of the cover 4, a screwdriver or similar tool The distance a is used for compensation purposes

  tolerance and also takes into account a possible displacement

  axial part 17 of the body, that is to say the

  notch 17, relative to the adjustment screws 2 a and 2 b because of the possible extent of the adjustment angles 21 In the device opposing the adjustments, represented on the left in FIG. 1, the axial length of the sleeve 9 is

  equal to the axial length of the cap 4 The diameter in-

  Dl of the end 26a, near the cap, of the through hole 26 corresponds to the inside diameter of the

socket 9 a.

  In the case of the device opposing the readjustment

  elements, represented on the right in FIG. 1, the axial length of the socket 9 b is greater than the axial length of the cap 4 The internal diameter D 2 (FIG. 2) of the widened end 26 b, on the cap side, of the hole passing 26 is greater than the outside diameter D 3 (figure 3) of the socket 9 b, the end 11, body side 1, of the socket 9 b protruding into the enlarged end 26 Thanks to this overlap any application of axial force by a

  screwdriver or the like on the cap 4 is made impossible

  ble The possible axial play of the end il relative to the part 17 of the body can then be significantly greater

  to play a in the case of the device opposing the readjustments

  elements, represented on the left in figure 1 The device

  opposing the adjustments, shown on the right in the figure

  gure 1, is therefore particularly suitable for ranges of

  relatively larger and up to

  than one full turn of the adjusting screw.

  1 1 The cover 4, the annex part 5, the socket 9 a; 9 b as well as the spacers 12 intended to break are

  made in a single piece of plastic, the ma-

  plastic being preferably hard to brittle This ensures that in the event of manipulation of the device opposing the adjustments the nominal breaking spacers 12

  break to provide a visually perceptible indication

  ceptible and permanent of a manipulation carried out or attempted. Instead of retaining the cap 4, in fixed rotation by friction connection way, as described above, on the head 3 of the adjusting screw 2 a; 2 b it can also be obtained, by a suitable embodiment of the head 3 and of the cap 4, an assembly in shape connection and fixed in rotation of the cap and the

set screw.

  The screen forming part 17 of the body is retained

  axially captive between the annular shoulder

  area 22 of the adjusting screw 2 a; 2 b and the cap 4 and / or the socket 9 a, 9 b The fact of providing in the part 17 of the body stops 6 and 7 fixed in rotation and associated with the

  body allows to equip existing carburetors, to post-

  riori, of the device according to the invention without it being necessary

  make modifications to carburetor body 1 itself

  even Simply replace the adjustment screws

  2 a and 2 b, then slide, after adjusting the retaining screws

  glage, the common screen 17 on the narrowed parts 3 a and 3 b and to place by pressing a cap, provided with the sleeve

  connected to the cap by means of spacers intended

  born to be broken, on the head 3 of each of the adjustment screws. In the embodiment shown in FIGS. 4 to 6, the socket 9 c surrounding the cover 4 with a

  radial clearance r is connected, at its end it is

  killed on the side of the body 1, fixedly to the part 17 of the body in the form of a screen; had preference, share L-le 1 u

  body is made in one piece with the socket 9 c The

  end 10 of socket 9 c as well as end 13 of

  cap 4 end substantially in a common plane 14.

  As shown in particular in the top view of FIG. 6, the socket 9c is obtained by sparing in

  screen 17 a bore or countersink with a partial diameter-

enlarged.

  Cap 4 is received entirely inside

  of socket 9c and has, according to the example of realization

  tion of Figures 1 to 3, an axial annex 5 which engages in a slot 18 of the body the ends, located in the peripheral direction, of which form stops 6 and 7 The adjusting screw is first passed through the hole 26 of the screen 17 and screwed into the body 1 as well as roughly preset Then the cap 4 is slid over the head of the adjusting screw 3 located in the socket 9 c and on which said cap is retained in dynamic connection

  or shaped Thus the cap 4 is connected, in an im-

  axially and fixedly rotatable in the peripheral direction, to the adjusting screw 2 a The cover 4

  is slid into place up to a collar 50 of the retaining screw

  glage 2 a so that the collar 50 separates the head 3 from the

  both of the adjusting screw 2 a The collar 50 can at the same time serve to limit the axial screwing depth of the adjusting screw 2 a; the screen 17 is retained between the collar and the body 1 To secure the screen 17 in fixed rotation, a second adjusting screw has passed through

  the second hole 26 (figure 6) and screwed into the body The as-

  fixed rotation subject can also be obtained

  by pins, dowels or the like.

  Due to the small clearance r a screwdriver cannot be engaged between the socket 9 c and the cover 4 without

  cause damage to the Oiff A 4 from so-rte qe des ïitani-pula-

  tempted or carried out are recognized at all times

  by visible and permanent damage to the

cap 4.

  In the embodiment of Figures 7 and 8 the screen 17 is nonexistent; the stops 6 and 7 as well as the socket 9 c are formed directly on the body 1 For this it can be provided on the body 1 a dome or the like to be machined accordingly and preferably made in one piece with the body The annexed part 5 limiting the adjustment angle is provided as an outer axial rib on the outer periphery of the cover 4; She's spreading

  substantially over the entire height of the cover 4 At the

  tie annex 5 in the form of a rib are associated, in 's-

  annular space between the cap 4 and the socket 9 c, the bu-

  tees 6; 7 integral with the body (FIG. 8) and by which

  the operating range of the adjusting screw 2 a is limited.

  Since the radial distance r from the socket 9 c to the cap 4 is small enough that it is not possible to insert a screwdriver therein to remove the cap 4,

  without damaging it, by leveraging, manipulating

  The invisible position of the adjusting screw 2A is excluded.

  In order to secure the adjustment screw 2 a, screwed into the body 1, in the desired position of rotation, there is arranged, transversely to the threaded hole 26, a flange

  of plastic material 51 which projects into the ta-

  raudé 26 The thread of the adjusting screw 2 a is inserted into the plastic rod 51 so as to obtain

  braking of the screw, which suddenly prevents a displacement

  undesirable cementing of the adjusting screw 2 due to oscil-

* lations or the like.

Claims (10)

  I Device fitting to the adjustments for an adjustment screw (2 a, 2 b) retained so as to be able to rotate in a body (1), in particular for an adjustment screw of a carburetor, such as for example a carburetor with membrane or the like, of a machine tool such as a chain motor saw, the device consisting of a cap (4) fixedly fixed in rotation on the head (3) of the adjusting screw (2a , 2 b) and by a party   appendix (5) provided on the cover (4) and to which is   company, in the direction of rotation of the adjusting screw (2 a, 2 b), a stop (6, 7) secured to the body, characterized in that the cap (4) is surrounded, with a slight play   radial (r), of a socket (9 a, 9 b, 9 c) arranged sensibly-   coaxially with the cap, in that the cap (4) is   received appreciably over its entire length avil i l nt Ir-   eur of the socket (9 a, 9 b, 9 c) and in that the socket (9 a, 9 b, 9 c) is connected to the cap (4) or to the part (17) of the body having the stop.   2 Device opposing the adjustments, according to claim 1, characterized in that the end (13), remote from the body (1), the cap (4) and the end   (10), away from the body, from the socket (9 a, 9 b) ends   substantially in a common plane (14).   3 Device opposing the adjustments according to claim 1 or 2, characterized in that the end (10) of the sleeve (9a, 9b), which is remote from the body (1), is connected by the intermediate radial spacers (12) intended to break, at the end (13) of the cap (4) which is remote from the body and in that the end (11), body side (1), of the socket (9 a; 9 b) extends to the vicinity of the part (17) of the body having the stop (6, 7).   4 Device opposing adjustments according to   claim 2 or 3, characterized in that the   t Oses (12) intended for CL to break lie in the plane (14).   5 Device opposing adjustments, se-   Any of the preceding claims, charac-   terized in that the body (1, 17) and the end (11), side   body (1, 17), of the sleeve (9 b) overlap axially-   is lying. 6 Device opposing adjustments according to   any one of the preceding claims, character-   in that the stopper (6, 7) is between the bush (9 c) and the cap (4).   7 Device opposing the adjustments ntt lelnn   any one of claims 1 to 5, characterized in   that the annex part (5) extends, substantially parallel-   the axis (8) of the adjusting screw (2 a, 2 b), axial-   in the direction of the body (1, 17), the sleeve (9 c) preferably being made in one piece with the part (17) of the body which presents the stop.   8 Device opposing adjustments according to   any one of the preceding claims, character-   in that the stop (6, 7) is formed by one end of a slot (18) which, formed in the part (17) of the body   and extending in the direction of rotation, is longer   in the direction of rotation that the axial part an-   nex (5), which extends over a peripheral angle (20) preferably around 900.   9 Device opposing adjustments according to   any one of the preceding claims, character-   se in that the cap (4) is retained in dynamic connection on the head (3) of the adjusting screw (2 a, 2 b) and in that it is provided, in particular on the side of the bottom (15 ) of Coife D which is far from the body () an opening   engagement (16) for an operating tool.   10 Device opposing adjustments according to   any one of the preceding claims, character-   in that the part of the body which is fixed in rotation and has the stop (6, 7) is a screen (17) crossed by the adjusting screw (2 a, 2 b), the screen (17) being of preference   crossed by two adjusting screws (2 a, 2 b).